PM5351 Datasheet, PDF (53/393 Pages) PMC-Sierra, Inc – Quad 155 Mbit/s ATM and Packet Over SONET/SDH Physical Layer Device

S/UNI-TETRA
DATASHEET
PMC-1971240
ISSUE 7
PMC-Sierra, Inc.
PM5351 S/UNI-TETRA
SATURN USER NETWORK INTERFACE (155-TETRA)
Pin Name
DTPA[4]
DTPA[3]
DTPA[2]
DTPA[1]
Type
Output
(POS)
Pin
No.
K22
K23
L20
L21
Function
POS-PHY Direct Transmit Packet Available
(DTPA[4:1]).
These output signals provide direct status indication
of when some programmable number of bytes is
available in the transmit FIFO, for the corresponding
port. When transitioning high, DTPA indicates that
the transmit FIFO has enough room to store data.
The transition level is selected by the TXFP
Transmit Packet Available Low Water-mark
(TPALWM[7:0]) register. When DTPA transitions
low, it indicates that the transmit FIFO is either full
or near full as selected by the TXFP Transmit
Packet Available High Water-mark (TPAHWM[7:0])
register. This last option provides the Link Layer
system with some look ahead capability in order to
avoid FIFO overruns and smoothly transition
between PHY’s.
DTPA[4:1] are updated on the rising edge of
TFCLK.
TMOD
Input
(POS)
F22 POS-PHY Transmit Word Modulo (TMOD) signal.
TMOD indicates the size of the current word. TMOD
is only used during the last word transfer of a
packet, at the same time TEOP is asserted. During
a packet transfer every word must be complete
except the last word, which can be composed of 1
or 2 bytes. TMOD set high indicates a 1-byte word
(present on MSB’s, LSB’s are discarded) while
TMOD set low indicates a 2-byte word.
TMOD is considered valid only when TENB is
simultaneously asserted and the S/UNI-TETRA is
selected via TADR[4:0].
TMOD is sampled on the rising edge of TFCLK.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
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